Clear skies and warm air are forecast for the holiday weekend, but all that will change by Tuesday when a cold storm blows in from Alaska with rain, wind and maybe even a little Bay Area snow, the National Weather Service said Friday.

The expected half inch of rain in San Francisco is sorely needed. Only 0.89 of an inch has fallen in the city since New Year's Day, the fifth-driest start to a calendar year since records have been kept starting in 1849, said Steve Anderson, a forecaster with the weather service.

On average, San Francisco collects 6.15 inches of rain in January and February.

"We're hoping for a miracle March," Anderson said.

But first comes February and a fine run of weather over the Presidents Day weekend, courtesy of a high-pressure bubble that has been keeping storms well to the north.

"It'll be a great time to get out and enjoy the weather wherever you can," said Anderson, who is taking his own advice - he's heading for Yosemite.

Some Bay Area locations will see the 70s, a sharp contrast from the highs expected when cold, "soaking rain" arrives Tuesday, Anderson said. Hilltops above 3,000 feet may see snow, he said.

So if you head to the top of Mount Diablo, elevation 3,849 feet, "with your hands stretched high, you might be able to grab a snowflake or two," Anderson said.